<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <style>
    * {
      padding: 0;
      margin: 0;
    }

    .wrap {
      width: 300px;
      margin: 100px auto 0;
    }

    table {
      border-collapse: collapse;
      border-spacing: 0;
      border: 1px solid #c0c0c0;
      width: 300px;
    }

    th,
    td {
      border: 1px solid #d0d0d0;
      color: #404060;
      padding: 10px;
    }

    th {
      background-color: #09c;
      font: bold 16px "微软雅黑";
      color: #fff;
    }

    td {
      font: 14px "微软雅黑";
    }

    tbody tr {
      background-color: #f0f0f0;
    }

    tbody tr:hover {
      cursor: pointer;
      background-color: #fafafa;
    }
  </style>
</head>
<body>
<div class="wrap">
  <table>
    <thead>
    <tr>
      <th>
        <input type="checkbox" id="j_cbAll"/>
      </th>
      <th>商品</th>
      <th>价钱</th>
    </tr>
    </thead>
    <tbody id="j_tb">
    <tr>
      <td>
        <input type="checkbox"/>
      </td>
      <td>iPhone8</td>
      <td>8000</td>
    </tr>
    <tr>
      <td>
        <input type="checkbox"/>
      </td>
      <td>iPad Pro</td>
      <td>5000</td>
    </tr>
    <tr>
      <td>
        <input type="checkbox"/>
      </td>
      <td>iPad Air</td>
      <td>2000</td>
    </tr>
    <tr>
      <td>
        <input type="checkbox"/>
      </td>
      <td>Apple Watch</td>
      <td>2000</td>
    </tr>

    </tbody>
  </table>
</div>
<script>
  var j_cbAll = document.getElementById('j_cbAll'); // 全选按钮
  var j_tbs = document.getElementById('j_tb').getElementsByTagName('input');

  j_cbAll.onclick = function () {
    for (var i = 0; i < j_tbs.length; i++) {
      j_tbs[i].checked = this.checked;
    }
  }
  for(var i = 0; i < j_tbs.length; i++){
    j_tbs[i].onclick = function () {
      for(var i = 0; i < j_tbs.length; i++){
        if (j_tbs[i].checked === false){
          j_cbAll.checked = false;
          return;
        }
      }
      j_cbAll.checked = true;
    }
  }
</script>
</body>
</html>